Selective degassing valve for containers of aromatic or odorous products, such as coffee and the like

ABSTRACT

A one-way degassing valve ( 4 ) for containers of aromatic products such as coffee and the like, comprising a valve body ( 5, 6 ), a valve element ( 12 ) and a filter ( 17 ), comprising a selective filter layer ( 21   a ), preferably consisting of activated charcoal, which allows the passage of low molecular weight gases, such as carbon dioxide, and retains high molecular weight gases that constitute the product&#39;s aroma, and an oxygen and CO 2  adsorbing layer ( 21   b ), able to eliminate the residual oxygen present in the container and suitably reduce the amount of CO 2 .

DESCRIPTION

[0001] The present invention relates to a valve for containers ofaromatic or in any case odorous products, especially particulate orpowder products, such as coffee, detergents, organic liquids and thelike.

[0002] Valves of the above-mentioned type are obviously already knownand are commonly called degassing valves. They are one-way valves whichare normally applied to the upper wall of the container and whosepurpose is to allow the gases developed by the product, for examplecoffee, to escape from the container, avoiding the possible buildup ofinternal overpressure, which would cause bulging and/or tearing of thecontainer itself, and at the same time to prevent air from entering thecontainer as this would impair the quality of the product.

[0003] The one-way valves used at present serve this purpose perfectly,opening when slight internal overpressures occur and closing immediatelywhen they cease.

[0004] However, these valves present great drawbacks due to thefollowing considerations.

[0005] Fresh (newly packaged) coffee generates a mixture of gases insidethe container, consisting mainly of carbon dioxide and, in a smallerpercentage, of so-called aromas, which are characterized by complexmolecular chains.

[0006] The one-way valves currently in use utilize porous filters, whosesole purpose is to prevent the escape of particles of coffee. In theevent of overpressures inside the container, therefore, they allow bothcarbon dioxide and the product's aromas to escape, as well as othergases. Valves of this type are described, for example, in Italianpatents 823800 and 971505.

[0007] Although specific reference is made in this description tocoffee, that is to a product with a pleasant aroma, the same problemarises for odorous products in general, such as the detergents andorganic liquids mentioned above, for which it would be desirable toavoid the escape of odours, in this case unpleasant ones.

[0008] EP-0 659 657 B1 describes a valve of the selective type whichallows the gases that form in the package to escape, retaining theproduct's aromas. It has been noted, however, that such a type of valvedoes not allow the complete escape of the oxygen, which tends to oxidizethe product with which it comes into contact, detracting from thequality thereof.

[0009] It is therefore necessary to close the container after havingcreated a high vacuum by a procedure that tends to slow down theproduction rates of the packaging machines or else it is necessary tocarry out washing with inert gas, again by means of quite a costlyprocedure.

[0010] The package has a slightly bulging appearance according to theoverpressure necessary for opening the valve.

[0011] The object of the invention is to avoid said drawbacks, and topreserve the nature of the product more or less intact, reducing to aminimum or preventing the escape of aromas or odours, and at the sametime ensuring that the oxygen present in the package is eliminated andthe carbon dioxide is reduced so that the package does not appear tobulge.

[0012] This object is achieved, according to the invention, by providinga degassing valve equipped with a selective filter, which allows thepassage of molecules of carbon dioxide and other gases, and traps themolecules that determine the product's aroma and odours, not allowingthem to escape, and which eliminates the residual part of the oxygen,thus enhancing the quality of the product.

[0013] Coffee is known to develop a large amount of CO₂, equivalent toas much as two or three times its volume, after toasting. Most of thisCO₂ is eliminated through the valve, whereas the residual amount isabsorbed by the filter to such an extent as to further reduce theresidual internal pressure inside the package, thereby giving thepackage a pleasant appearance without bulges.

[0014] Porous filters or molecular sieves can be used as selectivefilters. However, in the tests performed it has been observed that thefilters that best perform this selector function are compounds based onactivated charcoal, diatomaceous earth, silica, etc, which in any casecan be modified by adding additives which make them specific to theindividual organic requirements. The oxygen, on the other hand, isadsorbed through oxidoreduction reactions, reactions of addition toorganic substances, as already known to the art. The same applies toCO₂.

[0015] Further characteristics of the invention will be made clearer bythe detailed description that follows, referring to a purely exemplaryand therefore non-limiting embodiment thereof, illustrated in theappended drawings, in which:

[0016]FIG. 1 is an exploded diagrammatic view of a degassing valveequipped with a selective, oxygen-adsorbing filter according to theinvention.

[0017]FIG. 2 is a diagrammatic sectional view of the valve in FIG. 1,installed on a container, shown partially;

[0018]FIG. 3 is a diagrammatic axonometric view of a container equippedwith such a valve.

[0019]FIG. 4 is a diagrammatic side elevational view of a degassingvalve according to the invention before installation on a container.

[0020] With reference to these figures, in FIG. 3 reference numeral 1designates in a general way a container for aromatic products,particularly coffee, of the flexible or semi-rigid type.

[0021] In the example illustrated, the selective valve according to theinvention is installed on the front part of the container. For thispurpose, a small hole 3 is made in the sheet material, or laminate, ofthe container, beneath which a degassing valve, designated as a whole byreference numeral 4, is applied, said valve being heat-welded or gluedto the laminate 2.

[0022] The degassing valve 4, whose general structure can be consideredsubstantially known, comprises a base plate 5 and a cap 6 seatedtherein. The cap 6 has near its lower edge an annular groove 7 whichengages in a corresponding annular projection 8 provided on the bottomof the plate 5. Above the projection 8 is a flat annular wall 9, whichsurrounds a central disk 10 provided with holes 11.

[0023] Between the cap 6 and the plate 5 is interposed a rubberdiaphragm 12 acting as the valve proper, the peripheral part of whichrests on said flat annular wall 9 of the plate, which is spread with aviscous layer 13, in order to provide a better seal. The diaphragm 12 ispressed against the plate 5 by an opposing projection 14 provided in theupper wall of the cap 6, in which a bleed or vent hole 15 is alsoprovided.

[0024] The bottom of the plate 5 is shaped so that underneath it, belowthe disk 10, a seating 16 is provided for a filter 17 that will bedescribed in greater detail below.

[0025] The valve 4 is fixed to the sheet 2 by welding or gluing thatfollows an annular path 18 along the upper outside edge of the plate 5.

[0026] The valve works as follows.

[0027] Under normal conditions, the rubber diaphragm 12 is applied inabutment against the flat wall 9 of the plate 5 and, thanks to thepresence of the viscous layer 13, creates a seal both against the escapeof the gases contained inside the container 1, and against the entry ofair from the outside.

[0028] In the event of overpressures inside the container 1, thediaphragm 12 lifts from the wall 9, allowing the gases to escape,passing through the holes 11, the space that is created between thediaphragm 12 and the wall 9, the hole 15 in cap 6 and the hole 3 formedin the laminate 2 into the outside environment. When normal conditionsare restored, the diaphragm 12 comes down again, preventing air fromentering the container by the opposite route to that previouslydescribed.

[0029] In order to prevent the coffee aromas from escaping when thegases are being discharged from the container, a selective type filter17 is used, comprising a plurality of porous layers with interposedadsorbent layers.

[0030] In the preferred embodiment illustrated in FIG. 1, the filter 17comprises an upper porous disk 19 a, beneath which is disposed anadsorbent layer of activated charcoal 21 a, a second porous disk 20,then an oxygen and CO₂ adsorbing layer 21 b, consisting of materialscontaining ferrous ions, for example, and a third porous disk 19 b. Thewhole can be retained in the seating both by simple pressure and bygluing or welding of a filtering wall.

[0031] The adsorbent layer 21 b is disposed more to the inside of thepackage, that is, nearer to the product, to improve the reduction ofoxygen and CO₂ in the package.

[0032] According to an alternative embodiment, the two adsorbent layers21 a and 21 b can be incorporated into a single layer comprising bothactivated charcoal and a substance that adsorbs oxygen and CO₂, thuseliminating one porous disk.

[0033] Another alternative consists in making two side-by-side chambersin the seating recess 16, said chambers separately containing theactivated charcoal or the like and the oxygen and CO₂ adsorbent. In thiscase the chamber containing the oxygen adsorbent may even not be incommunication with the upper area of the valve, since it has the solefunction of adsorbing the oxygen and CO₂.

[0034] In order to preserve the activity of the adsorbents and inparticular of the oxygen adsorbent, which would degrade rapidly uponcontact with air, these are suitably protected before being installed onthe package, for example by means of an underlying impermeable layer.This could consist of a multi-layer laminate composed, for example, of apeel-away polyester, aluminium and polyethylene film 24, as shownschematically in FIG. 4. In this case a ribbon or tape 24 would beobtained, on which the valves are welded and this would serve as aloader for the valves on the packaging lines. The ribbon of barrier filmwould be detached from the valve at the time of application to thedesired point of the package. Alternatively, the ribbon of barrier filmcan be punched onto the valve and remain welded thereto, to beperforated at the time of application of the valve to the package, thuspreventing contact with the oxygen before the adsorbent begins to do itswork.

[0035] With a filter thus structured, the gases given off by the coffee,before passing through the rubber diaphragm 12, are filtered through theactivated charcoal 21 a, which retains the majority of them, that is thearomas, thus maintaining a higher concentration inside the package. Atthe same time, the oxygen and CO₂ adsorbent 21 b eliminates the oxygenpresent in the package and maintains a suitable CO₂ content, eliminatingthe overpressure necessary to open the valve.

[0036] The role of the CO₂ adsorbent is thus to eliminate theoverpressure present in the bag after the degassing procedure performedby the valve, in order to make the pressure inside and outside thepackage equal, eliminating bulging.

[0037] Application of the selective filter essentially acts as a barrieragainst the escape of volatile organic substances (aromas, fragrances,odours, etc.) from inside the container through degassing of theproduct. The filter component that removes the oxygen present in thepackage allows oxidization of the contents to be reduced, increasing theproduct's shelf life.

[0038] The system described above can find a use whenever it isnecessary to allow gases to escape from the package, avoiding thepassage of organic molecules and also reducing the oxygen and CO₂content.

1. A degassing valve for containers of aromatic and odorous products,comprising a valve body (5, 6) and a mobile valve element (12) of theone-way type, positioned on the valve body (5, 6) and a filter (17)engaging said valve body and positioned in front of the product, able toprevent the passage of particles of product, wherein said filter (17)comprises a selective filtering layer (21 a) which allows the passage ofgas with “simple” molecules, such as carbon dioxide, and retains gaseswith complex molecular chains, which constitute the product's aromas,characterized in that said filter (17) also comprises an oxygen and/orcarbon dioxide adsorbent (21 b) able to remove the residual oxygen inthe container.
 2. A valve according to claim 1, characterized in thatsaid selective filtering layer (21 a) and said oxygen and carbon dioxideadsorbent layer (21 b) are overlapping and interposed between disks ofporous material (19 a, 20, 19 b).
 3. A valve according to claim 1 or 2,characterized in that said oxygen and carbon dioxide adsorbent layer (21b) is disposed innermost in the container and therefore nearest theproduct.
 4. A valve according to claim 1, characterized in that saidoxygen and carbon dioxide adsorbent (21 b) is incorporated in saidselective filtering layer (21 a), constituting a single layer enclosedbetween two porous disks (19 a, 19 b).
 5. A valve according to claim 1,characterized in that said selective filtering layer (21 a) and saidoxygen and carbon dioxide adsorbent layer (21 b) are disposed alongsideand separated from each other.
 6. A valve according to claim 5,characterized in that said oxygen and carbon dioxide adsorbing layer isnot in communication with the outside of the container.
 7. A valveaccording to any one of the preceding claims, characterized in that saidoxygen and carbon dioxide adsorbent layer (21) comprises materialscontaining ferrous ions.
 8. A valve according to any one of thepreceding claims, characterized in that said selective filtering layer(21 a) consists of activated charcoal.
 9. A valve according to any oneof the preceding claims, characterized in that said selective filteringlayer (21 a) and said oxygen and carbon dioxide adsorbent layer (21 b)are contained in a seating (16) formed in said valve body (5).
 10. Avalve according to claim 1, wherein said valve body comprises a baseplate (5) housing said filter (17) and an opposing cap (6) provided withrespective holes (11, 15) and said valve element (12) is a rubberdiaphragm normally pressed against the plate (5) so as to close saidholes (11).
 11. A degassing valve according to any one of the precedingclaims, characterized in that it is applied to a wall of a container (1)for aromatic products, such as coffee and similar products that give offodours.
 12. A valve according to claim 11, characterized in that it isprotected by an underlying impermeable layer (24) before application tothe container.
 13. A valve according to claim 12, characterized in thatsaid impermeable layer (24) consists of a peel-away film that is removedwhen the valve is applied to the container.
 14. A valve according toclaim 12, characterized in that said impermeable layer (24) consists ofa film that is perforated at the time of application of the valve to thepackage.
 15. An airtight container for products that develop odorousgases, such as coffee and the like, with a one-way degassing valve (4)provided with at least one selective filtering layer (21 a) whichprevents aromas or odours from escaping, and at least one oxygen andcarbon dioxide, adsorbent layer (21 b) able to eliminate the residualoxygen and carbon dioxide present in the container.